Spatial power-combining devices, such as a Qorvo® Spatium® spatial power-combining device, are used for broadband radio frequency power amplification in commercial and defense communications, radar, electronic warfare, satellite, and various other communication systems. Spatial power-combining techniques are implemented by combining broadband signals from a number of amplifiers to provide output powers with high efficiencies and operating frequencies. One example of a spatial power-combining device utilizes a plurality of solid-state amplifier assemblies that form a coaxial waveguide to amplify an electromagnetic signal. Each amplifier assembly may include an input antenna structure, an amplifier, and an output antenna structure. When the amplifier assemblies are combined to form the coaxial waveguide, input antennas may form an input antipodal antenna array, and output antennas may form an output antipodal antenna array.
In operation, an electromagnetic signal is passed through an input port to an input coaxial waveguide section of the spatial power-combining device. The input coaxial waveguide section distributes the electromagnetic signal to be split across the input antipodal antenna array. The amplifiers receive the split signals and in turn transmit amplified split signals across the output antipodal antenna array. The output antipodal antenna array and an output coaxial waveguide section combine the amplified split signals to form an amplified electromagnetic signal that is passed to an output port of the spatial power-combining device.
An antenna for conventional spatial power-combining devices typically includes a metal antenna signal conductor and a metal antenna ground conductor deposited on opposite sides of a substrate, such as a printed circuit board. The printed circuit board provides a desired form factor and mechanical support for the antenna signal conductor and the antenna ground conductor; however, the printed circuit board can become increasingly lossy at higher frequencies, thereby limiting the combining efficiency and achievable output power of the antenna.
An amplifier for a conventional spatial power-combining device is typically located between an input antenna structure and an output antenna structure within each amplifier assembly of a plurality of amplifier assemblies. When the plurality of amplifier assemblies are coaxially arranged, the amplifiers are thus radially arranged within the spatial power-combining device. This configuration positions a separate amplifier along each of multiple signal paths such that an incoming signal may be split, amplified by multiple amplifiers in parallel, and combined. However, the output power and efficiency of typical configurations can have limitations related to thermal capabilities of the amplifiers. As the operating temperature of an amplifier increases, the efficiency can decrease and thereby limit the output power.